Synthetic resinous materials are prepared in a variety of manners such as mass polymerization suspension polymerization, solution polymerization and emulsion polymerization. For many resinous materials it is desirable that they be prepared by an emulsion polymerization technique in order that the desired particle size molecular weight or grafting reaction is more readily obtained by the emulsion polymerization route than by solution, suspension or mass polymerization. Latex solids have been recovered most frequently by adding an electrolyte to the latex, usually with heating and agitation to cause the latex particles to agglomerate into macro particles which are readily filtered, washed and dried. Typical processes are discussed in U.S. Pat. Nos. 3,248,455; 3,345,430; and 3,438,923, the teachings of which are herewith incorporated by reference thereto. For some purposes the use of electrolyte in coagulation results in undesired retention of the emulsifier employed in the emulsion polymerization and oftentimes retention of at least some of the electrolyte employed for the coagulation. In order to overcome the problem of electrolyte retention, nitrile polymer latexes have been coagulated by shear coagulation. Shear coagulation is a process wherein a latex is subjected to mechanical shear until at least a major portion of the latex particles have agglomerated and in the event that the system which is subjected to shear has a solids content of about 20 to 30 weight percent, the shear coagulated product is a more or less grainy paste. U.S. Pat. No. 3,821,348 discloses a shear coagulation process wherein the resultant paste of a nitrile polymer latex is extruded and placed in hot water for a period of time and the resultant extrude washed and dried.
It would be desirable if there were available an improved process for the recovery of latex solids.
It would also be desirable if there were available an improved process for the recovery of latex solids which required minimal energy.
It would also be desirable if there were available an improved process for the recovery of latex solids which required minimal quantities of water and steam.